Internal restraint for delivery of self-expanding stents

ABSTRACT

A medical device delivery system comprises a catheter having a catheter shaft with a proximal region and a distal region. The catheter shaft has a pull wire lumen therein. An expandable medical device is disposed about medical device receiving region of the catheter shaft. The expandable medical device has a reduced configuration and an expanded configuration. The system further comprises a retractable retaining wire, at least a portion of which is coiled about the expandable medical device and retains the expandable medical device in the reduced configuration. One end of the retractable retaining wire terminates in a pull-wire. The pull-wire extends into the pull-wire lumen to the proximal region of the catheter shaft.

BACKGROUND OF THE INVENTION

[0001] Stents are used in a wide variety of locations in the bodyincluding in coronary arteries, renal arteries, peripheral arteriesincluding iliac arteries, arteries of the neck and cerebral arteries.Stents are also used in other bodily locations including but not limitedto arteries, veins, biliary ducts, urethras, fallopian tubes, bronchialtubes, the trachea, the esophagus and the prostate.

[0002] Stents typically are self-expanding, balloon expandable or ahybrid of the two. Self-expanding stents may be made of shape memorymetals such as nitinol, shape memory polymer materials, or constructedof non-shape memory metals but of a design which exhibits self-expansioncharacteristics. Balloon expandable stents are typically delivered on aballoon and the balloon is used to the expand the stent. Hybrid stentshave both self-expanding properties and balloon expanding properties.

[0003] Typically, stents are delivered to desired bodily locations viathe use of catheters. A catheter comprising a stent is introduced into abodily vessel and advanced through the vasculature in the body until thestent is positioned in a desired location. Usually, the stent will beprotected by a retractable sheath which is disposed about the stent andwhich increases the profile of the delivery catheter. The sheath may beremoved from about the stent via the use of a retraction device such asa pull-wire, pull rod or a catheter tube which is connected to thesheath. As part of the removal, the sheath may optionally be rolled offof the stent. In the case of self-expanding stents, the sheath may alsorestrain the stent from self-expanding. Once at the desired location,the stent is either allowed to self-expand or is balloon expanded. Inthe case of self-expanding stents, the self-expansion may occur as aresult of the removal of the sheath from about the stent.

[0004] Unfortunately, many self-expanding stent delivery systems, inparticular those using retractable sheaths, employ cumbersome and/orbulky deployment mechanisms.

[0005] There remains a need for medical device delivery systems ingeneral and stent delivery systems in particular which avoid the use ofcumbersome and/or bulky deployment mechanisms.

[0006] There also is a need for expandable medical devices which arecapable of being retained on a catheter with a retractable retainingmember of minimal profile.

[0007] The entire content of all of the patents listed within thepresent patent application are incorporated herein by reference.

[0008] The invention in various of its embodiments is summarized below.Additional details of the invention and/or additional embodiments of theinvention may be found in the Detailed Description of the Inventionbelow. An abstract of one of the embodiments of the invention is alsoprovided below.

SUMMARY OF THE INVENTION

[0009] In one embodiment, the present invention is directed to adelivery system for delivering a medical device to a location in a bodylumen. The delivery system comprises a catheter having a catheter shaftwith a proximal region and a distal region. The catheter shaft has apull wire lumen therein. At least a portion of the distal region definesa medical device receiving region. An expandable medical device isdisposed about the medical device receiving region. The expandablemedical device has a reduced configuration and an expandedconfiguration. The system further comprises a retractable retainingwire, at least a portion of which is coiled about the expandable medicaldevice and retains the expandable medical device in the reducedconfiguration. The wire may be characterized as a ribbon or may haveother shapes and configurations. One end of the retractable retainingwire terminates in a pull-wire. The pull-wire extends into the pull-wirelumen to the proximal region of the catheter shaft.

[0010] In another embodiment, the invention is directed to a medicaldevice delivery system comprising a catheter having an outer member anda retractable inner member. The catheter has a proximal region and adistal region. At least a portion of the distal region of the innermember defines a medical device receiving region. An expandable medicaldevice having a reduced configuration and an expanded configuration isdisposed about the medical device receiving region of the inner memberin the reduced configuration. The expandable medical device comprises aplurality of interconnected struts. One or more flexible members, eachhaving a first end and a second end, are looped about the medical devicereceiving region of the inner member retaining the medical device in thereduced configuration. Each end of the flexible members is engaged toone or more struts.

[0011] In yet another embodiment, the invention is directed to anexpandable medical device having a reduced configuration and beingexpandable to an expanded configuration. The expandable medical devicecomprises a plurality of interconnected struts which define an internaltubular passage. The expandable medical device further comprises one ormore flexible members. Each of the one or more flexible members has afirst end and a second end and extends into the internal tubularpassage. Each end of the one or more flexible members is engaged to oneor more struts.

[0012] In another embodiment, the invention is directed to a medicaldevice delivery system comprising a catheter member having a proximalregion and a distal region. At least a portion of the distal region ofthe catheter member defines a medical device receiving region. Anexpandable medical device having a reduced configuration and an expandedconfiguration, is disposed about the medical device receiving region ofthe catheter member in the reduced configuration. The expandable medicaldevice further has one or more engagement members. Each engagementmember has a first end and a second end. The first end is engaged to alocation on the expandable medical device and the second end isreleasably engaged to the medical device receiving region of thecatheter member.

[0013] In another embodiment, the invention is directed to a medicaldevice delivery system comprising a catheter member having a proximalregion and a distal region. At least a portion of the distal region ofthe catheter member defines a medical device receiving region. Anexpandable medical device having a reduced configuration and an expandedconfiguration is disposed about the medical device receiving region ofthe catheter member in the reduced configuration. The system furthercomprises one or more engagement members, each having a first end and asecond end. The first end of each engagement member is engaged to alocation on the expandable medical device and the second end of eachengagement member is engaged to a location on the medical devicereceiving region of the catheter member. The expandable medical deviceis expanded from the reduced configuration to the expanded configurationwhen the first ends of the engagement members are released from theexpandable medical device or the second ends of the engagement membersare released from the medical device receiving region.

[0014] In yet another embodiment, the invention is directed to anexpandable medical device having a reduced configuration and beingexpandable to an expanded configuration. The expandable medical devicecomprises one or more engagement members, each of which has a first endand a second end. The first end of each of the engagement members isengaged to a location on the expandable medical device and the secondend of each of the one or more engagement members extends radiallyinward from the first end. The engagement members are constructed andarranged to releasably engage a medical device receiving region of acatheter member.

[0015] The invention is also directed to methods of securing a medicaldevice such as a stent to a catheter. In accordance with one inventivemethod, a stent is provided as is a catheter member. The catheter membermay be in the form of a tube having a passage therethrough or in theform of a solid member. One or more engagement members, as disclosedabove, extends from the stent and is releasably secured to the cathetermember.

[0016] In accordance with another inventive method, one or moreengagement members extending from the catheter member is releasablysecured to the stent.

[0017] In yet another embodiment of the inventive methods, a stenthaving one or more flexible members, each having a first end secured tothe stent and a second end secured to the stent, is provided. Theflexible members form loops. A catheter member is inserted in the loopsthereby retaining the stent in the reduced configuration.

[0018] A detailed description of the invention in its variousembodiments is provided below.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0019] A detailed description of the invention is hereafter describedwith specific reference being made to the drawings in which:

[0020]FIG. 1 is a side perspective view of an embodiment of theinvention wherein a stent is shown retained about a delivery catheter bya retaining wire.

[0021]FIG. 2 is a side perspective view of the embodiment shown in FIG.1 wherein the stent is shown expanding as a result of retraction of aretaining wire.

[0022]FIG. 2a is a side perspective view of an embodiment of theinvention wherein a stent is shown retained about a delivery catheter bya pair of retaining wires extending from a single port.

[0023]FIG. 2b is a side perspective view of an embodiment of theinvention wherein a stent is shown retained about a delivery catheter bya pair of retaining wires with each wire extending from a respectiveport.

[0024]FIG. 3 is a side perspective view of the embodiment shown in FIG.2 wherein the stent is shown expanded as a result of fully retractingthe retaining wire from the stent;

[0025]FIG. 4 is a side perspective view of an alternative embodiment ofthe invention wherein the retaining wire is threaded through the strutsof the stent.

[0026]FIG. 5 is a side perspective view of an embodiment of theinvention wherein a stent includes internal members for retaining thestent in a reduced configuration about a shaft of a delivery catheter.

[0027]FIG. 6 is a cross-sectional view of the embodiment shown in FIG.5.

[0028]FIG. 7 is a side perspective view of the embodiment shown in FIG.5, wherein the stent has been expanded by withdrawing the shaft from theretaining members.

[0029]FIG. 8 is a cross-sectional view of the embodiment shown in FIG.7.

[0030]FIG. 9 is a cross-sectional view of an alternative of theembodiment shown in FIG. 7 wherein retaining members are configured tocorrespond to the circumference of the stent after delivery.

[0031]FIG. 10 is a profile view of an embodiment of the inventionwherein a stent includes internal members for retaining the stent in areduced configuration about a shaft of a delivery catheter.

[0032]FIG. 11 is a profile view of the embodiment of the invention shownin FIG. 10 wherein following delivery of the stent the retaining membersare configured to correspond to the circumference of the stent afterdelivery.

[0033]FIG. 12 is a side perspective view of an embodiment of theinvention wherein a stent includes internal hooks of shape memorymaterial for retaining the stent in a reduced configuration about ashaft of a delivery catheter.

[0034]FIG. 13 is a cross-sectional view of the embodiment shown in FIG.12.

[0035]FIG. 14 is a side perspective view of the embodiment shown in FIG.12, wherein the stent has been expanded by activation of the shapememory hooks which are then disengaged from the catheter shaft therebyreleasing the stent to expand.

[0036]FIG. 15 is a cross-sectional view of the embodiment shown in FIG.14.

DETAILED DESCRIPTION OF THE INVENTION

[0037] While this invention may be embodied in many different forms,there are described in detail herein specific exemplary embodiments ofthe invention. This description is an exemplification of the principlesof the invention and is not intended to limit the invention to theparticular embodiments illustrated.

[0038] For the purposes of this disclosure, unless otherwise indicated,identical reference numerals used in different figures refer to the samecomponent.

[0039] As indicated above, the present invention is directed to novelexpandable medical devices as well as their associated delivery systems.

[0040] In one embodiment of the invention such as is shown in FIG. 1 adelivery system, indicated generally at 10 is shown. Delivery system 10includes a catheter 12. The catheter 12 may be any form of cathetersuitable for the delivery of a medical device. In the embodiment shown,catheter 12 includes a shaft 11 which defines a lumen 14 through which apull back wire 16 may move. Pull back wire 16 extends proximally to aproximal hub 18 of the catheter where it may be operated. Desirably, thepull back wire 16 terminates in an readily actuatable mechanism 20 whichmay be actuated to cause proximal retraction of the wire 16. An exampleof a suitable retraction mechanism 20 is described in U.S. Pat. No.5,968,052, the entire contents of which is incorporated herein byreference.

[0041] At the distal region 22 of the catheter 12, the cathetercomprises a retaining wire 24 which terminates in the pull back wire 16.The retaining wire 24 and pull back wire 16 may be of one piececonstruction or may be in the form of a retaining wire and a pull backwire which are welded, soldered or adhesively joined together. Theretaining wire 24 may also be characterized as a wire of material.

[0042] The retaining wire 24 and pull back wire 16 combination exits thepull back wire lumen 14 through a port 26 in the side wall 28 of thecatheter shaft 11. Where the wire 24 exits port 26, the wire 24 definesa relatively straight elongated proximal portion 30. The wire 24 may bereadily drawn into the lumen 14 through port 26 when the pull back wire16 is actuated.

[0043] The distal portion 32 of the wire 24 is coiled about anexpandable medical device, such as a stent 34. The coiled portion of thewire retains the stent in a reduced profile configuration about a stentretaining area 36 of the catheter shaft 11. In the embodiment shown inFIG. 1, the stent 34 may be any type of stent including a self-expandingstent or a balloon expandable stent. Where the stent is balloonexpandable or requires mechanical seating, the stent retaining area 36of the catheter 12 may be or may include a medical balloon or otherexpansion device. Where the stent retaining area 36 includes a balloon,the catheter shaft 11 will include an inflation lumen or other means forinflating the balloon as is known in the art. The inflation lumen may beprovided as part of catheter shaft 11.

[0044] In FIG. 2, the system 10 is shown during retraction of the wire24. As the pull back wire 16 is proximally drawn, the wire 24 isretracted from about the stent 34 and into the lumen 14 through port 26.In the embodiment shown in FIG. 2, the stent 34 is a self-expandingstent and is shown expanding from the distal end as the wire 24 iswithdrawn. As is shown in FIG. 3, once the wire 24 is withdrawn fromabout the stent 34, the stent is allowed to fully expand. Once stent 34is fully expanded and positioned in the vessel, the catheter 12 may bewithdrawn.

[0045] Depending on the location of the port 26, the wire 24 may beconfigured to be withdrawn from the proximal end or the distal end ofthe stent as desired. In another embodiment of the invention shown inFIGS. 2a-2 b multiple wires 24 may be provided through one or more portsto allow for simultaneous expansion of both ends of the stent or medialexpansion as desired.

[0046] In FIG. 2a the system 10 is shown wherein a pair of retainingwires 24 a and 24 b are drawn through a single port 26. The wires 24 aand 24 b are retracted proximally through the lumen 14. However,depending on the position of the stent 34 relative to the port 26portions of the wires 24 a and/or 24 b may be pulled distally as thewire(s) are drawn through the port 26 during retraction.

[0047] In the embodiment shown, the port 26 is positioned centrally inthe stent retaining area 36. Where simultaneous retraction of both wires24 a and 24 b is to be conducted, wires 24 a and 24 b may extendproximally to a single pull back wire 16. When the wires 24 a and 24 bare retracted the proximal and distal ends of the stent are initiallyexposed simultaneously before any other portion of the stent. Byallowing the ends of the stent to be freed before the medial portion,the ends of the stent may be allowed to expand or begin expanding priorto the middle region of the stent.

[0048] Where it is desirable to permit a particular end of the stent 34to expand before the other end, one of the wires 24 a or 24 b may beretracted first. In such an embodiment, each wire 24 a and 24 b mustextend to a distinct and separate pull back wire, to allow forindividualized retraction.

[0049] In another embodiment of the invention shown in FIG. 2b, thesystem 10 employs a pair of wires 24 a and 24 b each of which extendsfrom a respective port 26 a and 26 b. Preferably, the ports 26 a and 26b are positioned in the stent retaining area 36 such that when a stent34 is placed thereabout, the wires 24 a and 24 b extend over the ends ofthe stent and are directed over the medial region of the stent. If thewires 24 a and 24 b are retracted simultaneously, the medial region ofthe stent is initially freed before the stent ends, thereby allowing thecenter of the stent to begin expansion prior to the ends.

[0050] The number and placement of ports as well as wires may be variedas desired. The embodiments shown in FIGS. 2 and 2a-2 b are merelyexamples of the wide range of configurations which may be embodied bythe present invention. In addition to the number and position of theports and wires, other embodiments may be employed such as theembodiment shown in FIG. 4, wherein the wire 24 may be threaded throughselected struts 38 of the stent 24 to provide a more secure engagementof the stent in the reduced profile configuration. As the wire 24 isretracted, the wire 24 is un-threaded from the struts 38 as it isproximally withdrawn through the lumen 14.

[0051] In the embodiments shown in FIGS. 1-4, the wire(s) 24 may beconstructed of any material capable of retaining a stent 34 in a reducedprofile state, such as is shown in FIG. 1, but which is flexible enoughto be readily withdrawn from the stent such as is shown in FIGS. 2 and3. Optionally, to facilitate retraction of the wire 24 from the stent34, the wire 24 may be constructed from a shape memory material such asnitinol and/or a shape memory polymer. Some examples of suitable shapememory polymers include but are not limited to: acrylate-based polymers,polyurethane-based polymers, polylactide-based polymers andpolynorbornene based polymers.

[0052] The use of a shape memory material in wire 24 may provide thewire with the capability to uncoil from the stent 34 when the shapememory property is activated by a change in temperature, or pH in thewire 24 or surrounding area. The shape memory material may betemperature activated by the heat of the body or heat may be deliveredto the wire 24 through the pull back wire 16. Alternatively, a warmsaline bolus may be injected into the lumen 14 to increase thetemperature surrounding the wire 24 prior to or during retraction. Inone embodiment of the invention where the shape memory material of thewire 24 is pH activated, a bolus of pH-buffered saline may be injectedinto lumen 14 to change the pH of the area surrounding wire 24.

[0053] Turning to FIGS. 5-6, another embodiment of the invention isshown wherein a self-expanding stent 34 is retained in the reducedprofile configuration by internally mounted members 40 which engage thecatheter shaft 11. The shaft 11 may be a solid member or may have one ormore lumens therein, as desired. Members 40 extend between two ends 44and 46. Ends 44 and 46 are each engaged to a strut 38 or other portionof the stent 34 in such a manner that when the member 40 is looped overthe catheter shaft 11, the members retain the stent 34 in the reducedprofile configuration and prevent the stent 34 from self-expanding. Whenmultiple members 40 are distributed throughout the length of the stentinterior 42 and engaged to the shaft 11, the stent 34 is drawn radiallyinward to the reduced profile configuration shown in FIGS. 5 and 6.

[0054] The members 40 may be any material which can be configured intostrands suitable for placement within the lumen or interior 42 of astent 34. In some embodiments of the invention, members 40 may beconstructed from a material that can stretch elastically at least 50percent of the original loop length, in a manner similar to that of arubber band. Some examples of suitable elastic materials include but arenot limited to silicone and/or polyurethane. Members 40 may be stretchedaround the shaft 11 prior to delivery of the stent 34.

[0055] In order to allow the stent 34 to self-expand, the shaft member11 is withdrawn from the stent interior 42 as shown in FIG. 7. In someembodiments, the shaft 11 may be a wire or other elongate member. Theshaft 11 and/or members 40 may be coated with a biocompatible lubricantto facilitate withdrawal of the shaft 11 from the interior 42. Thecatheter 12 includes a housing or other member 48 through which theshaft 11 may be withdrawn. The shaft 11 is capable of longitudinalmovement relative to the housing 48. The housing 48, prevents the stent34 from being shifted in position as the shaft 11 is withdrawn. Afterthe shaft 11 is withdrawn from the stent interior 42, the entirecatheter 12 including the housing 48 and shaft 11 may be withdrawn fromthe body. The invention also contemplates the use of other membersadjacent to the catheter shaft 11 which can act to retain the stent 34in place while the catheter shaft 11 is withdrawn.

[0056] As the shaft 11 is withdrawn, the individual members 40 aredisengaged from the shaft 11 thereby allowing the stent 34 toself-expand. As may be seen in FIG. 8, the members 40 are sufficientlylong and/or flexible enough to not interfere with the expansion of thestent 34. In some embodiments where the members 40 are configured tostretch elastically as previously described, when shaft 11 is withdrawnduring stent delivery, the members 40 may be configured to become asubstantially straight member extending from two points on the stent 34corresponding to ends 44 and 46, such as is shown in FIG. 9. Preferably,ends 44 and 46 are spaced fairly close together along the circumferenceof stent 34 so that the straightened member 40 would not encroach, orwould only minimally encroach, into the interior of the expanded stent34.

[0057] In some embodiments of the invention, members 40 may beconstructed from a superelastic or shape-memory material. Some examplesof suitable shape-memory materials may include but are not limited to:nitinol, shape-memory polymers and/or superelastic titanium alloys.Where members 40 are made from shape-memory materials the individualmembers 40 do not appreciably stretch in length, but instead members 40have the capacity to take one shape when it is looped around the shaft11 and return to another default shape after the shaft 11 is withdrawn.

[0058] An example of another configuration of members 40 is shown inFIG. 10 wherein each member 40 has a single extension member 45extending from end 44 along the circumference of the stent 34. Theextension members 45 extend inward into the stent interior 42 to engagethe catheter shaft 11 with a shaft engagement member 60. Preferably,shaft engagement member 60 is a hook or ring shaped portion of themember 40 which is engaged to extension member 45. Engagement member 60may be constructed from the same material or a different material thanextension member 45. When the shaft 11 is withdrawn, the members 40 mayattain the default shape or may be configured to acquire a new shapewherein the extension members 45 draw the shaft engagement members 60 toa position along the plane of the stent 34 such as is shown in FIG. 11.

[0059] In yet another embodiment of the invention shown in FIGS. 12-15,the system 10 is configured to provide a self-expanding stent 34 withthe capability of being self-expanded without the need to withdraw theshaft 11 from the stent interior 42 prior to stent delivery. Inaddition, the stent 34 is retained about the catheter shaft 11 withoutthe use of a retaining sheath, sleeve, or retaining wires as previouslydiscussed.

[0060] In the embodiment shown in FIGS. 12 and 13 the stent 34 includesat least one, and desirably a plurality, of interior mounted members inthe form of hooks, loops or weaves 50. When the stent 34 is held in thereduced profile state prior to delivery, the interior ends 52 of eachmember 50 are engaged to the catheter shaft 11. As shown in FIG. 12, theends 52 are preferably partially disposed about the catheter shaft 11.The members may be engaged to the catheter shaft 11, or may be engagedto other members 50 which overlap to retain the stent 34 to the shaft 11in the unexpanded state.

[0061] The exterior end 54 of each member 50 is engaged to one or morestruts 38 of stent 34 and restrains the stent from self-expanding. Insome embodiments of the invention, the members 50 may be integral withthe stent 34 and include ends 52 that are removably engaged to thecatheter shaft 11 prior to stent delivery.

[0062] The members 50 are constructed at least partially from a shapememory material. Suitable shape memory materials include any the shapememory materials disclosed above and may be temperature or pH activated.In order to release the stent 34 to self-expand, at least the interiorends 52 of the members 50 are subjected to a change in temperature or pHsufficient to cause the ends 52 to relax their shape and release thestent 34 from the catheter shaft 11 such as is shown in FIGS. 14 and 15.Once the stent is released, the catheter 12 may be withdrawn.

[0063] In some embodiments of the invention, the members 50 may beconfigured to retract into the circumference of the stent therebyensuring that the members do not extend inward into the stent interior42 once the stent 34 is fully expanded.

[0064] The change in temperature required to cause transformation of thehooks 50 may be accomplished in a variety of ways. In at least oneembodiment the shaft 11 defines a lumen 14 through which a wire 56 maybe passed. For the purposes of this disclosure, the term wire isincludes metal wires, polymer fibers, optical fibers, or other elongatemembers. In at least one embodiment of the invention, wire 56 may be anoptical fiber which is advanced through the shaft 11 to locationsadjacent to the hook ends 52. The optical fiber may be used to transmitlaser light to the hooks 50 in order to transform the hooks 50 andrelease the ends 52 from the catheter shaft 11. Alternatively, wire 56may be a wire or other heating or electrically conductive element whichmay heat the hooks 50 to release the ends 52 from the shaft 11. In theembodiments where a wire is used to heat the hooks 50, the catheter 12itself may be a heat conductive wire or material thereby removing theneed for lumen 14 and reducing the profile of the catheter 12 further.

[0065] In still another embodiment, the lumen 14 may be used to transmita heated bolus and/or pH-buffered bolus of saline to the stent interior42 whereupon the increase in temperature and/or pH provided by the boluscauses release of the ends 52 from the shaft. Other methods of providingheat or a change in temperature to the interior of a stent, such as maybe known, may also be utilized in the present invention.

[0066] It should also be noted that the members 50 may also beconstructed to be fixedly engaged to the catheter shaft 11 such that theshape memory aspect of the hooks 50 allows the exterior ends 54 torelease the stent struts 38. In such an embodiment the members 50 may beconfigured to be drawn inward toward the catheter shaft 11 to ensure areduced profile for retraction of the catheter 12 from the body.

[0067] The invention is also directed to methods of securing a medicaldevice such as a stent to a catheter. In accordance with one inventivemethod, a stent is provided as is a catheter member. The catheter membermay be in the form of a tube having a passage therethrough or in theform of a solid member. One or more engagement members, as disclosedabove, extends from the stent and is releasably secured to the cathetermember.

[0068] In accordance with another inventive method, one or moreengagement members extending from the catheter member is releasablysecured to the stent.

[0069] In yet another embodiment of the inventive methods, a stenthaving one or more flexible members, each having a first end secured tothe stent and a second end secured to the stent, is provided. Theflexible members form loops. A catheter member is inserted in the loopsthereby retaining the stent in the reduced configuration.

[0070] In addition to being directed to the specific combinations offeatures claimed below, the invention is also directed to embodimentshaving other combinations of the dependent features claimed below andother combinations of the features described above.

[0071] The above disclosure is intended to be illustrative and notexhaustive. This description will suggest many variations andalternatives to one of ordinary skill in this art. All thesealternatives and variations are intended to be included within the scopeof the claims where the term “comprising” means “including, but notlimited to”. Those familiar with the art may recognize other equivalentsto the specific embodiments described herein which equivalents are alsointended to be encompassed by the claims.

[0072] Further, the particular features presented in the dependentclaims can be combined with each other in other manners within the scopeof the invention such that the invention should be recognized as alsospecifically directed to other embodiments having any other possiblecombination of the features of the dependent claims. For instance, forpurposes of claim publication, any dependent claim which follows shouldbe taken as alternatively written in a multiple dependent form from allprior claims which possess all antecedents referenced in such dependentclaim if such multiple dependent format is an accepted format within thejurisdiction (e.g. each claim depending directly from claim 1 should bealternatively taken as depending from all previous claims). Injurisdictions where multiple dependent claim formats are restricted, thefollowing dependent claims should each be also taken as alternativelywritten in each singly dependent claim format which creates a dependencyfrom a prior antecedent-possessing claim other than the specific claimlisted in such dependent claim below.

1. A delivery system for delivering a medical device to a body location, the delivery system comprising: a catheter, the catheter having a catheter shaft having a proximal region and a distal region, the catheter shaft defining a pull-wire lumen, at least a portion of the distal region defining a medical device receiving region; an expandable medical device disposed about the medical device receiving region, the expandable medical device having a reduced configuration and an expanded configuration, the expandable medical device further having proximal and distal device ends; at least one retractable retaining wire, at least a portion of the at least one retractable retaining wire coiled about at least a portion of the expandable medical device and retaining the expandable medical device in the reduced configuration, one end of the at least one retractable retaining wire terminating in at least one pull-wire, the at least one pull-wire extending into the pull-wire lumen to the proximal region of the catheter shaft.
 2. The delivery system of claim 1 wherein the at least one retractable retaining wire is characterized as one or more ribbons.
 3. The delivery system of claim 1 wherein the at least one retractable retaining wire is constructed from a shape memory material.
 4. The delivery system of claim 1 wherein the at least one retractable retaining wire is constructed from at least one material of the group consisting of nitinol, acrylate-based polymers, polyurethane-based polymers, polynorbornene-based polymers, polylactide-based polymers, platinum, tungsten, titanium, stainless steel, nickel and any combinations thereof.
 5. The delivery system of claim 1 wherein the medical device is a stent.
 6. The delivery system of claim 5 wherein the stent comprises a plurality of interconnected struts, the at least one retractable retaining wire being threadingly coiled about selected struts of the stent.
 7. The delivery system of claim 1 wherein the medical device receiving region comprises a medical balloon, the delivery system further comprising an inflation lumen, the inflation lumen in fluid communication with the medical balloon.
 8. The delivery system of claim 7 wherein the medical device is balloon expandable.
 9. The delivery system of claim 1 wherein the catheter shaft includes a side wall, the side wall defining at least one lumen port, the at least one pull-wire extending proximally from the proximal end of the at least one retractable retaining wire and passing through the at least one lumen port to enter into the pull-wire lumen.
 10. The delivery system of claim 1 wherein the at least one retractable retaining wire is constructed and arranged to uncoil from the medical device when the at least one pull-wire is retracted.
 11. A delivery system for delivering a medical device to a body location, the delivery system comprising: a catheter, the catheter having an outer member and a retractable inner member, the catheter having a proximal region and a distal region, at least a portion of the distal region of the inner member defining a medical device receiving region; an expandable medical device having a reduced configuration and an expanded configuration, the expandable medical device disposed about the medical device receiving region of the inner member in the reduced configuration, the expandable medical device comprising a plurality of interconnected struts; one or more flexible members, each of the one or more flexible members having a first end and a second end, each end of the one or more flexible members being engaged to one or more struts, each of the one or more flexible members being looped about the medical device receiving region of the inner member, thereby retaining the medical device in the reduced configuration thereabout.
 12. The delivery system of claim 11 wherein the expandable medical device is expanded from the reduced configuration to the expanded configuration when the retractable inner member is proximally retracted from within the medical device.
 13. The delivery system of claim 11 wherein the medical device is a self-expanding stent.
 14. The delivery system of claim 11 wherein the inner member is a wire.
 15. The delivery system of claim 11 wherein the medical device mounting region of the retractable inner member includes a lubricious surface.
 16. An expandable medical device having a reduced configuration and being expandable to an expanded configuration, the expandable medical device comprising: a plurality of interconnected struts, the plurality of interconnected struts defining an internal tubular passage, one or more flexible members, each of the one or more flexible members having a first end and a second end and extending into the internal tubular passage, each end of the one or more flexible members being engaged to a strut.
 17. The expandable medical device of claim 16 wherein each of the one or more flexible members is constructed and arranged to removably engage a catheter member and retain the expandable medical device in the reduced state about the catheter member.
 18. The expandable medical device of claim 17 in combination with a catheter member, the expandable medical device disposed about the catheter member, each of the one or more flexible members at least partially and removably disposed about the catheter member, the flexible members being of sufficient length to allow the expandable medical device to expand to the expanded configuration when the catheter member is removed from within the expandable medical device.
 19. The expandable medical device of claim 18 in the form of a self-expanding stent.
 20. A delivery system for delivering a medical device to a body location, the delivery system comprising: a catheter member, the catheter member having a proximal region and a distal region, at least a portion of the distal region of the catheter member defining a medical device receiving region; and an expandable medical device having a reduced configuration and an expanded configuration, in the reduced configuration the medical device being disposed about the medical device receiving region of the catheter member, the expandable medical device further having one or more engagement members, each of the one or more engagement members having a first end and a second end, the first end of each of the one or more engagement members engaged to a location on the expandable medical device, in the reduced configuration the second end of each of the one or more engagement members releasably engaged to the medical device receiving region of the catheter member or to another of the one or more engagement members.
 21. The delivery system of claim 20 wherein the expandable medical device expands from the reduced configuration to the expanded configuration when the second end of the one or more engagement members is released from the medical device receiving region of the catheter member or from another of the one or more engagement members.
 22. The delivery system of claim 20 wherein the one or more engagement members are constructed from at least one material of the group consisting of nitinol, acrylate-based polymers, polyurethane-based polymers, polynorbornene-based polymers, polylactide-based polymers, platinum, tungsten, titanium, stainless steel, nickel and any combinations thereof.
 23. The delivery system of claim 21 wherein the one or more engagement members are at least partially constructed from a temperature sensitive shape memory material.
 24. The delivery system of claim 22 wherein the second end of each of the one or more engagement members is constructed at least partially from the temperature sensitive shape memory material.
 25. The delivery system of claim 24 wherein the catheter member includes a lumen therein.
 26. The delivery system of claim 25 wherein the lumen has a heating element therein, the heating element constructed and arranged to increase the temperature of the second end of each of the one or more engagement members.
 27. The delivery system of claim 25 wherein the heating element is selected from at least one member of the group consisting of a fiber optic wire, an electrically conductive wire, an electrically resistive wire, a saline bolus, and any combination thereof.
 28. The delivery system of claim 20 wherein the catheter member is a heat conductive wire.
 29. The delivery system of claim 21 wherein the one or more engagement members are at least partially constructed from a pH sensitive shape memory material.
 30. The delivery system of claim 29 wherein the second end of each of the one or more engagement members is constructed at least partially from the pH sensitive shape memory material.
 31. The delivery system of claim 30 wherein the catheter member includes a lumen therein.
 32. The delivery system of claim 31 wherein the lumen is constructed and arranged to deliver a pH-buffered bolus of saline to the distal region of the catheter member.
 33. A delivery system for delivering a medical device to a body location, the delivery system comprising: a catheter member, the catheter member having a proximal region and a distal region, at least a portion of the distal region of the catheter member defining a medical device receiving region; an expandable medical device having a reduced configuration and an expanded configuration, in the reduced configuration the medical device being disposed about the medical device receiving region of the catheter member; and one or more engagement members, each of the one or more engagement members having a first end and a second end, in the reduced configuration the first end of each of the one or more engagement members being releasably engaged to a location on the expandable medical device or to another of the one or more engagement members, the second end of each of the one or more engagement members engaged to the medical device receiving region of the catheter member.
 34. The delivery system of claim 33 wherein the expandable medical device expands from the reduced configuration to the expanded configuration when the first end of the one or more engagement members is released from the location on the expandable medical device or from another of the one or more engagement members.
 35. The delivery system of claim 33 wherein the one or more engagement members are constructed from at least one material of the group consisting of nitinol, acrylate-based polymers, polyurethane-based polymers, polynorbornene-based polymers, polylactide-based polymers, platinum, tungsten, titanium, stainless steel, nickel and any combinations thereof.
 36. A delivery system for delivering a medical device to a body location, the delivery system comprising: a catheter member, the catheter member having a proximal region and a distal region, at least a portion of the distal region of the catheter member defining a medical device receiving region; an expandable medical device having a reduced configuration and an expanded configuration, the expandable medical device disposed about the medical device receiving region of the catheter member in the reduced configuration; one or more engagement members, each of the one or more engagement members having an engaged state and a released state, each of the one or more engagement members having a first end and a second end, the first end of each of the one or more engagement members engaged to a location on the expandable medical device and in the reduced configuration the second end of each of the one or more engagement members being engaged to a location on the medical device receiving region of the catheter member or to another engagement member; the expandable medical device being expanded from the reduced configuration to the expanded configuration when the one or more engagement members are transformed from the engaged state to the released state thereby causing the second ends of the one or more engagement members to be released from the medical device receiving region or the another engagement member.
 37. The delivery system of claim 36 wherein the one or more engagement members are constructed from at least one material of the group consisting of nitinol, acrylate-based polymers, polyurethane-based polymers, polynorbornene-based polymers, polylactide-based polymers, platinum, tungsten, titanium, stainless steel, nickel and any combinations thereof.
 38. An expandable medical device having a reduced configuration and being expandable to an expanded configuration, the expandable medical device comprising: one or more engagement members, each of the one or more engagement members having a first end and a second end, the first end of each of the one or more engagement members engaged to a location on the expandable medical device, the second end of each of the one or more engagement members extending radially inward from the first end and constructed and arranged to releasably engage a medical device receiving region of a catheter member.
 39. The expandable medical device of claim 38 wherein the one or more engagement members are at least partially constructed from a temperature sensitive shape memory material.
 40. The expandable medical device of claim 38 wherein the second end of each of the one or more engagement members is constructed at least partially from a temperature sensitive shape memory material.
 41. The expandable medical device of claim 38 wherein the one or more engagement members are constructed from at least one material of the group consisting of nitinol, acrylate-based polymers, polyurethane-based polymers, polynorbornene-based polymers, polylactide-based polymers, platinum, tungsten, titanium, stainless steel, nickel and any combinations thereof.
 42. The expandable medical device of claim 38 wherein the medical device is a self-expanding stent. 